Gubernator Jerzy, Drulis-Kawa Zuzanna, Kozubek Arkadiusz
Institute of Biochemistry and Molecular Biology, University of Wroclaw, Przybyszewskiego 63/77, 51-148 Wroclaw, Poland.
Int J Pharm. 2006 Dec 11;327(1-2):104-9. doi: 10.1016/j.ijpharm.2006.07.039. Epub 2006 Jul 25.
A new method for measuring gentamicin in liposomes fluorometrically is described. The assay is based on the reaction between the amino groups in the gentamicin molecule and o-phthaldialdehyde (OPA), under basic pH conditions; the product's fluorescence can be read directly on a simple fluorimeter. The effects of several factors (time of reaction, volume of the OPA reagent, and product stability) were investigated. The standard curve was linear in the concentration range of 0.5-4.0microg, showing an excellent determination coefficient of r(2)=0.99. Additionally, the influence of different liposomal lipids on gentamicin determination was tested. Liposomal lipids containing no free amino groups (PC, Chol, DOTAP) have no influence on the reaction when present in the reaction mixture. In contrast, amino groups containing lipid (SA) showed intense method interference. Therefore, a method of lipid extraction was adapted to remove undesired lipids. The described method was successfully utilised during 2 years of liposomal gentamicin experiments.
